Softimage Xsi: weighting a new snapped object !! help!

ive got a problem,, im working on a game model thats arlready weighted,,ive added some geometry ( a collar) that ive then point snapped to the existing geometry


its not extruded or anything from the original mesh( the model is going to have a number of different collars) ,,i go to weight and it works but when i move the shoulders the collar moves ,but its not snapped and following the edge of the chest like it should,,,


any solutions??


i was thinking i have to adjust the weighting ,,but i tried and it doesnt give me the results like it should,,,


PLEASE HELP!!!